Improve tool selection

What does this MR do and why?

Fix gitlab-org/modelops/ai-model-validation-and-research/ai-evaluation/ai-experiments#11 (closed)

Remove explicit "Here is an example of using this tool:" in <example> tag

This removes most of failures.

Remove tool list numbering

This removes (potentially) one failure. I think XML having text node may add cognitive complexity to LLM.

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